1. Field of the Invention
The present invention relates to a device, a system, a method and a program for navigation and also to a recording medium storing the program.
2. Description of Related Art
Vehicle navigation devices adapted to acquire traffic information (VICS data) on vehicle accidents, traffic jams and so on from a vehicle information communication system (VICS) and superimpose the acquired traffic information (on vehicle accidents, traffic jams and so on) on the map being displayed on a display unit for the purpose of notifying a user are known. Meanwhile, when a traffic jam occurs, drivers who want to avoid the traffic jam may make a detour to consequently give rise to a secondary traffic jam. Because the vehicle information communication system provides only the current traffic condition, drivers who make a detour, seeing the current traffic condition provided by the system, can be engulfed in a secondary traffic jam. Thus, there is a demand for improved vehicle navigation devices that allow users to avoid traffic jams and take the best route to get to the destination.
On the other hand, vehicle navigation devices adapted to predict the traffic condition for now and in the future by using statistic data on traffic jams obtained by statistically processing information on past traffic jams and notify users of the predicted traffic condition for now and in the future are known (for example, Japanese Patent Laid-Open Publication No. Hei 9-113290, p. 3, right column—p. 7, left column). A vehicle navigation device described in the above-cited patent document is adapted to provide a vehicle user with statistic traffic jam information as classified on the basis of the days of the week and the time zones of a day by superimposing the statistic traffic jam information on the map being displayed on the display unit. Thus, the vehicle user can predict the traffic jams that can take place now and those that can take place in the future according to the traffic jam information for the day of the week and the time zones of a day.
With the vehicle navigation device as disclosed in the above-cited patent document, the traffic jam information of which the vehicle user is notified is obtained by statistically processing traffic jam information in the past and hence based on the statistic traffic jam data of the past and only tells statistic facts on the traffic jams in a specific time zone on a specific day of the week. In other words, the vehicle user cannot recognize how the current traffic jams, if any, will progress with time. Additionally, the vehicle user may not have to make a detour if the current traffic jam on the road ahead is dissolved before the vehicle gets there. Thus, the vehicle user needs to recognize how the current traffic jams, if any, will progress with time in order for the vehicle to move smoothly. Then, the vehicle user needs to be notified of statistic information on traffic jams before and after the time zone and selects the route to take on the basis of the statistic information. However, it will be cumbersome for the vehicle user to recognize how the current traffic jams will progress with time while driving the vehicle.